You could call the gig at the Middle East Down on Jan. 14 a double header - a David Lowery double header. The singer-guitarist will be fronting both bands on the bill: the kind of eccentric Camper Van Beethoven and the bluesier, alt-rockier Cracker.A visit to the Northeast on MLK weekend, and an appearance at the Middle East, is a tradition both bands have taken up over the past decade.